JPH0772447A - Liquid crystal projector - Google Patents

Abstract

PURPOSE:To provide a liquid crystal projector where the durability of a polarizing plate is improved. CONSTITUTION:In this liquid crystal projector provided with a liquid crystal panel 31 on which a picture is formed, a projection lens 21 enlarging and projecting the picture formed on the panel 31, and a light source 1 emitting a luminous flux illuminating the panel 31; two polarizing plates 32 and 36 are arranged in parallel with the axis of polarization on the light incident side of the panel 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector using a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal projector has been known as a device for displaying an image on a large screen. In this liquid crystal projector, the light emitted from the light source is irradiated onto the liquid crystal panel, and the liquid crystal panel forms an optical image corresponding to the video signal to modulate the intensity of the irradiation light and allow the light to pass through. It is configured to be incident on a projection lens and magnify and project an optical image on a screen.

In such a liquid crystal projector,
When displaying a full-color image, for example, it is configured as shown in FIG. The light emitted from the projection light source is directed in one direction by the reflector 2 having a reflective surface formed as a parabolic surface, cuts heat rays and ultraviolet rays by the cut filter 3, and then reflects only green light. The G primary color light (green light) is separated by the dichroic mirror 4, and the R primary color light (red light) and the B primary color light (blue light) are separated by the R reflection dichroic mirror 5 that reflects only the red light.

The G primary color light separated by the G reflection dichroic mirror 4 is reflected by the reflection mirror 6, enters the G color condenser lens 7 and is condensed, and further includes an active matrix type liquid crystal panel for G color. It is incident on the liquid crystal unit 8 for G color. Then, after being intensity-modulated by an optical image corresponding to a G-system video signal formed on the liquid crystal panel of the liquid crystal unit 8, the liquid crystal unit 8 reflects the R reflection dichroic mirror 9 and the B reflection dichroic mirror 10 that reflects only blue light. Is transmitted to enter the projection lens 21 and is enlarged and projected on a screen (not shown).

The R primary color light separated by the R reflection dichroic mirror 5 is incident on the R color condenser lens 11 and is condensed, and is further incident on the R color liquid crystal unit 12 including the R color active matrix type liquid crystal panel. To do. The R formed on the liquid crystal panel of the liquid crystal unit 12
After being intensity-modulated by the optical image corresponding to the video signal of the system, the liquid crystal unit 12 enters the R reflection dichroic mirror 9, is reflected here, is synthesized by the G system optical image, and is transmitted through the B reflection dichroic mirror 10. Then, it enters the projection lens 21 and is enlarged and projected on the screen.

Further, the B primary color light separated by the R reflection dichroic mirror 5 is made incident on the B color condenser lens 13 and is condensed, and is directed to the B color liquid crystal unit 14 including the B color active matrix type liquid crystal panel. Incident. After being intensity-modulated by an optical image corresponding to a B-system video signal formed on the liquid crystal panel of the liquid crystal unit 14, the liquid crystal unit 13 enters the B reflection dichroic mirror 10 through the reflection mirror 15 and is reflected there. After being combined with the G and R combined optical images, they enter the projection lens 21 and are enlarged and projected on the screen.

The optical components 1 to 15 are the base member 2
It is held at 0.

On the other hand, unlike the above-mentioned structure, a single-plate type liquid crystal projector for enlarging and projecting with a projection lens by using a liquid crystal panel incorporating one color filter without performing color separation and color combination by a dichroic mirror is also available. Has been converted.

[0009]

By the way, the liquid crystal panel is currently in the trend of miniaturization and increase in the number of pixels. For example, in the configuration of FIG. There is a possibility that liquid crystal panels of a certain degree will become the mainstream. In that case, about 9 times the light amount of the current state is incident on the incident side polarizing plate, and the durability of the polarizing plate becomes a problem.

On the other hand, in a single-plate type liquid crystal projector, the amount of light that is not separated into R, G, and B enters one polarizing plate on the incident side, so that the durability of the polarizing plate still poses a problem.

As described above, in the cases of the above-mentioned two examples, there is a strong demand for higher brightness, so that a polarizing plate with high durability or a method of using a durable polarizing plate is desired.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a liquid crystal projector in which the durability of a polarizing plate is improved.

[00001]

A liquid crystal projector according to the present invention emits a light beam for illuminating the liquid crystal panel, an image forming liquid crystal panel, a projection lens for enlarging and projecting the image formed on the liquid crystal panel. In a liquid crystal projector including a light source means, at least two polarizing plates are arranged on the light incident side of the liquid crystal panel in parallel with the polarization axis.

Further, according to the present invention, in a liquid crystal projector having three liquid crystal panels for modulating light of three colors of red, green and blue, two polarizing plates are provided only on the incident side of the liquid crystal panel of blue light. It is characterized in that it is arranged parallel to the polarization axis.

[0014]

According to the present invention, the incident side polarizing plate of the liquid crystal panel is
By arranging one plate with the polarization axes parallel, the amount of light that passes through the incident side polarization plate and is incident on the liquid crystal panel is attenuated by about 85 to 90% compared to the case where one conventional polarization plate is arranged. To do. However, the amount of light incident on the second polarizing plate is attenuated to about 45% as compared with the first polarizing plate. Further, basically, the light incident on the second polarizing plate has its polarization axis aligned, so that the light is not absorbed and the temperature does not rise due to the light absorption. Further, even if the first polarizing plate deteriorates, the symptom of the deterioration is that the transmittance of red light tends to increase, and the transmittance of blue light, which is the factor that most deteriorates the polarizing plate, does not change much.

Therefore, the life of the second polarizing plate can be expected to be more than twice as long as that of the first polarizing plate due to the decrease in the amount of incident light and the decrease in temperature rise.

[0016]

Embodiments of the present invention will now be described with reference to the drawings. The present invention improves the durability of the polarizing plate of the liquid crystal panel used in the above-described liquid crystal projector of FIG. 1, and the description will focus on the configuration of the liquid crystal unit including the liquid crystal panel.

FIG. 2 is a sectional view showing a liquid crystal unit according to the first embodiment of the present invention, showing an example of arrangement of polarizing plates. In this figure, a polarizing plate 32 is provided on the incident side of the active matrix type liquid crystal panel 31 in the liquid crystal unit,
The polarizing plate 32 is attached and held on the plate glass 33. A polarizing plate 34 is also attached and held on the plate glass 35 on the emission side of the liquid crystal panel 31. As shown in the figure, both polarizing plates 32 and 34 are arranged on the liquid crystal panel 3 so that the plate glasses 33 and 35 attached respectively do not disturb the polarized light.
It is located on the first side. Further, in the present invention, the second polarizing plate 36 is provided on the incident side of the liquid crystal panel 31, and the plate glass 3 is provided.
It is affixed to 7.

When light enters from the direction of the arrow in the figure, about 55% of the light is cut by the first polarizing plate 36, and the polarization is adjusted. Therefore, the characteristics of the polarizing plate 36 are deteriorated due to deterioration due to light and deterioration due to temperature rise due to light absorption.

The deterioration of the polarizing plate 36 is as shown in FIG. 7 when, for example, white light that does not undergo color separation is irradiated. FIG. 7 shows data obtained when light from a 150 W metal halide lamp is converted into almost parallel light by a parabolic mirror, passed through an infrared ray and ultraviolet ray cut filter, and then irradiated onto a 1.7-inch polarizing plate. The high transmittance in the figure is the data when the polarization axis is parallel to the clean polarizing plate that is not deteriorated, and the low transmittance is the normal polarizing plate and the polarization axis are orthogonal to each other when the transmittance is low. The solid line is the initial data, and the dotted line is the data after 350 hours.

As shown in the figure, it can be confirmed that the polarization of the red light is disturbed and the light is leaked, but it can be seen that the characteristics on the blue side do not change much.

It has been confirmed by experiments that the polarizing plate is most severely deteriorated by blue light among red, blue and green, and is hardly deteriorated by red and green lights.
In that respect, the first polarizing plate 36 deteriorates, but it can be said that the initial performance is almost maintained in the point that the polarization of the blue light is adjusted and blocked.

45% of the light that has passed through the first polarizing plate 36 enters the second polarizing plate 32, but the polarization axes of the first polarizing plate 36 and the second polarizing plate 32 are the same. Almost 85
~ 90% of the light passes. Therefore, the temperature of the second polarizing plate 32 hardly rises due to the absorption of light. Further, since about 55% of the light is cut by the first polarizing plate 36, the deterioration due to the light is much less. Furthermore, the first
Even when the polarizing plate 36 of No. 2 is deteriorated, the polarization performance of blue light is almost maintained as shown in FIG.
There is no concern that deterioration due to light 2 will be accelerated. Therefore, the second polarizing plate 32 is expected to have a life longer than twice that of the first polarizing plate 36.

On the other hand, the light incident on the second polarizing plate 32 is
The polarization is further adjusted by the polarizing plate 32, and the liquid crystal panel 3
1 and is modulated here, and then enters the exit side polarization plate 34.

In the above structure, the second polarizing plate 32
Does not increase in temperature, but when the temperature of the plate glass 33 is distorted and the polarized light by the first polarizing plate 36 is disturbed, the second polarizing plate 32 is not attached to the plate glass and the single polarizing plate is used. Is better to hold.

Further, the first polarizing plate 36 and the second polarizing plate 3
It is preferable to change the material of No. 2 and use a dye-based polarizing plate having excellent temperature characteristics as the first polarizing plate 36 and an iodine-based polarizing plate having excellent transmittance as the second polarizing plate 32.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a sectional view showing a liquid crystal unit of a second embodiment of the present invention. The same parts as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted here to avoid duplication of description. Omit it. The difference between the second embodiment and the first embodiment is that two polarizing plates 3 having the same polarization axis are used.
This is the point where 2, 36 are attached to one plate glass 40.
With this structure, the glass member is reduced as compared with the first embodiment.

However, when the temperature of the first polarizing plate 36 rises, the plate glass 40 is distorted, the polarized light arranged by the first polarizing plate 36 is disturbed, and the light absorption by the second polarizing plate 32 increases. However, there is a possibility that two problems occur that the temperature rise of the first polarizing plate 36 directly adversely affects the second polarizing plate 32.

A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view showing a liquid crystal unit according to a third embodiment of the present invention. In this embodiment as well, the same parts as those in the first embodiment are designated by the same reference numerals to avoid duplication of description. The description is omitted here.

As shown in FIG. 4, in the third embodiment, the first polarizing plate 36 and the second polarizing plate 32 are
It is affixed to two glass panels 41 and 42 which constitute a liquid cooler. Then, the liquid cooling device has a radiation fin 4
3 is provided, and the refrigerant 44 is injected inside the liquid cooler.

With such a structure, the first polarizing plate 36 is particularly well cooled, and the heat resistance of the first polarizing plate 36 is improved. Further, by filling the space between the first polarizing plate 36 and the second polarizing plate 32 with a cooling liquid having substantially the same bending rate, surface reflection and the like are reduced and the amount of light used is increased.

In each of the above-described embodiments, an example in which the first polarizing plate 36 is provided in the vicinity of the incident side of the liquid crystal panel 31 has been described. However, in the fourth embodiment shown in FIG. In the plate glass 37 before the separation of the light
The first polarizing plate 36 attached to is arranged.
That is, the first before the heat ray and ultraviolet ray cut filter 3
The polarizing plate 36 is arranged. With this configuration, the liquid crystal units 8, 12, 14 are provided with the first polarizing plate 3
It is not necessary to provide 6. In FIG. 5, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted here to avoid duplication of description.

Next, FIG. 6 shows a fifth embodiment of the present invention. The basic configuration of the liquid crystal projector is the same as that in FIG. 1, and the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted here to avoid duplication of description.

As shown in FIG. 6, in this embodiment, the liquid crystal panel 31 of the liquid crystal unit 14 for blue has
In the structure like the first embodiment of the present invention, two polarizing plates are arranged on the incident side. That is, the second polarizing plate 32 is provided on the incident side of the liquid crystal panel 31 in the liquid crystal unit 14 and the plate glass 33 is provided.
Affixed to and retained on. A polarizing plate 34 is also attached and held on the plate glass 35 on the exit side of the liquid crystal panel 31. Then, the first polarizing plate 36 is provided by being attached to the plate glass 37 on the incident side of the liquid crystal panel 31.

As described above, by using the two incident-side polarizing plates for blue, which are at risk of deterioration, the other colors (green and red) that are not at risk of deterioration can be effectively used. , The blue that decreases a little by arranging two polarizing plates,
This can be achieved by controlling the amount of metal halide enclosed in the metal halide lamp and the cut-off characteristics of the dichroic mirror. Therefore, each of the three liquid crystal panels of red, blue and green has two incident side polarization plates. You can arrange one
As shown in FIG. 5, it is possible to more effectively use the light than disposing one polarizing plate before the light is separated by the dichroic mirror.

[0035]

As described above, according to the present invention, by arranging two incident side polarization plates of the liquid crystal panel with their polarization axes parallel to each other, the second polarization plate reduces the amount of incident light. Due to the decrease in the temperature rise, the life of the polarizing plate can be expected to be more than double that of the first polarizing plate, the polarizing plate is less deteriorated, and a bright projector can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an optical arrangement of a liquid crystal projector.

FIG. 2 is a cross-sectional view showing a liquid crystal unit portion of the first embodiment of the present invention.

FIG. 3 is a sectional view showing a liquid crystal unit portion of a second embodiment of the present invention.

FIG. 4 is a sectional view showing a liquid crystal unit portion of a third embodiment of the present invention.

FIG. 5 is a block diagram showing the configuration of a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing a fifth embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a change over time in a polarizing plate when irradiated with white light.

[Explanation of symbols]

 31 liquid crystal panel 32 first incident side polarizing plate 34 emission side polarizing plate 36 second incident side polarizing plate 33, 35, 37, 40 plate glass

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[Procedure amendment]

[Submission date] August 11, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Further, the B primary color light separated by the R reflection dichroic mirror 5 is made incident on the B color condenser lens 13 and is condensed, and is directed to the B color liquid crystal unit 14 including the B color active matrix type liquid crystal panel. Incident. After being intensity-modulated by an optical image corresponding to a B-system video signal formed on the liquid crystal panel of the liquid crystal unit 14, the liquid crystal unit 14 enters the B reflection dichroic mirror 10 through the reflection mirror 15 and is reflected there. After being combined with the G and R combined optical images, they enter the projection lens 21 and are enlarged and projected on the screen.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

The deterioration of the polarizing plate 36 is as shown in FIG. 7 when, for example, white light that does not undergo color separation is irradiated. FIG. 7 shows data obtained when light from a 150 W metal halide lamp is converted into almost parallel light by a parabolic mirror, passed through an infrared ray and ultraviolet ray cut filter, and then irradiated onto a 1.7-inch polarizing plate. In the figure, the high transmittance is the data when the normal polarization plate which is not deteriorated and the polarization axis are arranged in parallel, and the low transmittance is the normal polarization plate which is not deteriorated and the polarization axis is arranged orthogonally. The solid line is the initial data, and the dotted line is the data after 350 hours.

Claims (2)

[Claims] 1. A liquid crystal panel for forming an image, a projection lens for enlarging and projecting an image formed on the liquid crystal panel,
Light source means for emitting a luminous flux for illuminating the liquid crystal panel,
A liquid crystal projector comprising: a liquid crystal projector, wherein at least two polarizing plates are arranged on the light incident side of the liquid crystal panel in parallel with the polarization axis. 2. The liquid crystal projector according to claim 1, further comprising three liquid crystal panels for modulating light of three colors of red, green and blue, wherein two polarized lights are provided only on the incident side of the liquid crystal panel of blue light. A liquid crystal projector in which a plate is arranged in parallel with the polarization axis.